Such a medical instrument can be used, for example, as an endoscope or a surgical or minimally invasive instrument inserted into a body, through an opening in the body, in order to perform an operation in the interior of the body in the context of a minimally invasive procedure. Medical tools, for example forceps, a gripping arm, a cutting tool or the like, are inserted through the shaft into the interior of the body, in order to perform the required maneuver using the tool. Alternatively, a tool (also referred to as a manipulator) can be permanently installed on the tip of the shaft.
The shaft has at least two shaft segments connected to each other in an articulated manner. It is in this way possible, by pivoting the shaft segments relative to each other, to change the guide path for a tool and to guide the tool, by means of the shaft, even to sites that are difficult to access.
In a medical instrument known from U.S. Pat. No. 6,099,464, a flexible shaft is provided which, by application of a tensile force, can be curved in the area of its tip.
U.S. Pat. No. 6,036,636 discloses a medical instrument with a shaft which has two shaft segments connected to each other in an articulated manner. A wire engages on one shaft segment and is guided in the other shaft segment in such a way that, by pulling on the wire, one shaft segment can be pivoted relative to the other shaft segment.
In a medical instrument known from EP 1 972 259 A2, a shaft has two shaft segments connected to each other in an articulated manner. An actuation element in the form of a wire engages on one shaft segment and is coupled to a lever on the other shaft segment in such a way that, by pivoting the lever, one shaft segment can be adjusted relative to the other shaft segment and, in this way, the shaft can be kinked in the area of its tip.
If sites that are difficult to access in the interior of the body are also intended to be reached by means of such a medical instrument, or if a complex operating technique such as a single-port procedure is to be used, it is necessary to have several shaft segments which are connected to one another in an articulated manner and which can be pivoted relative to one another in order to guide the medical instrument to the operating site. In shaft arrangements of this kind, however, hinges generally form weak points, since the hinges have to be provided in a small space and are therefore slender in design and, in addition, they need to have passages for tools or data lines and supply lines or even light guides. Since forces can act on an associated hinge via a lever arm when the shaft segment is pivoted, the loading forces and moments on the hinge can be considerable.
There is therefore a need for a medical instrument with a shaft which has several shaft segments connected to one another in an articulated manner and in which acting forces are advantageously supported.